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WRGC Pinpointing Underground Gas Leaks

WRGC Pinpointing Underground Gas Leaks. Ron Six, Instructor Senior Utility Consultant AEGIS Insurance Services, Inc. 201/417-2487 RonaldSix@aegislimited.com. A E G I S. A ssociated E lectric G as I nsurance S ervices. AEGIS Background Information.

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WRGC Pinpointing Underground Gas Leaks

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  1. WRGCPinpointing Underground Gas Leaks Ron Six, Instructor Senior Utility Consultant AEGIS Insurance Services, Inc. 201/417-2487 RonaldSix@aegislimited.com

  2. A E G I S AssociatedElectricGasInsuranceServices

  3. AEGISBackground Information • Utility Mutual Insurance Company • (member owned) • Formed in 1975 by 22 gas utilities • Electric Utilities began joining in 1977 • 375 members – 95% utilities and related energy

  4. Our main job is not finding & fixing leaks Our main job is public safety

  5. Pinpointing Is not an exact science.It is a developed skill which is learned and perfected through your mistakes and your successes.

  6. Major Causes of Leaks • Corrosion • Mechanical failure • Improper installation • Improper design • Faulty materials • 3rd Party Damage - “Dig-Ins”

  7. #682 #686 4” Plastic Main 45 PSI ASH ST Water Main Dead Cast Iron Gas Main

  8. The“Find and Fix Syndrome” The cure for this is to ask yourself a question “Where is the gas”? If you can answer the question that the gas is not affecting people and it is not affecting property you are cured. You must ask yourself this question on every leak before you get into the “repair” mode.

  9. Our main job is not finding & fixing leaks Our main job is public safety

  10. Detect Pinpoint Repair

  11. gas? r w e h the e is Evaluating The Leak Where is the gas?

  12. Evaluating The Leak • W • H • E • R • E here is the gas? ow much is there? xtent of hazard (migration) elation to other structures valuate/evacuate

  13. Factors Affecting Gas Migration • Soil type • Soil moisture • Surface cover • Line pressure • Depth of burial • Leak size and age • Change in elevation=slope • Path of least resistance

  14. Centering = Where is the gas? • Pinpointing = Where is the leak? • The leakmustbe centeredbefore it is pinpointed

  15. Centering The Leak • Probe holes must be of sufficient depth • Test all available openings • “Zero out” N-S-E-W • You must have sufficient information to make a good judgement Be Careful – “Don’t make a leak, looking for a leak.”

  16. Springfield, MA Recent Natural Gas Incidents

  17. Methods Of Locating The Line • Maps • Records • System experience • Electronic locators 1. Basic principles of operation 2. Inductive vs. Conductive 3. Overcoming problems

  18. Consistency = Success • Exact location of main, services etc. • Size of test hole (aeration is the key) • Depth of test hole (must be consistent) • Location of test holes (same side of main) • Instrument use (consistency in testing)

  19. PLACEMENT OF DRILL HOLES • Where and how many? • What size test holes? • How deep? • How far apart?

  20. Size of the Test Hole ½” Test Hole 1” Test Hole

  21. Size of the Test Hole ½” Test Hole 1” Test Hole 4x’s the Aeration From the 1” Test Hole vs. the ½” Test Hole

  22. The Size of the test hole is critical Pinpointing with a ½” test hole Pinpointing using a 1” test hole

  23. Minnich Hornet Drill

  24. SAVEANOTHERMISSEDEXCAVATION

  25. #404 #402 #400 30% Gas @ Foundation Wall Concrete Sidewalk 90% Gas @ Curb 4” Bare Steel 45 PSI OLD MAIN STREET

  26. Use Of Soil Purger (cont’d) • The soil purger is your best friend or worst enemy, depending on where and how it is used

  27. Types of Soil Purgers

  28. #404 #402 #400 Never purge near foundation 30% Gas @ Foundation Wall Concrete Sidewalk 90% Gas @ Curb Purge Away From Foundation This will draw the gas away from the building and block the gas from migrating to the foundation wall 8” CI UP OLD MAIN STREET

  29. Grade 1 Leak Repairs (Did you find “a” leak or did you find “the” leak?) • You mustnotleave a Grade 1 Leak indication as long as the conditions that got you there are still present. If the readings went from 30% gas to 3% gas at the foundation it is still a technical Grade 1 leak. Purge the soil, get the readings to 0%, wait and make sure that the readings do not return.

  30. 60% Gas Curb 8” Steel UP CWP Maple Street 15% Gas

  31. 60% Gas 8-10’ 8-10’ Curb 8” Steel UP CWP 50% 70% 75% Maple Street Service Line 15% Gas

  32. 60% Gas Curb 35% 15% 0% 8” Steel UP CWP 0% 10% 40% 45% 50% 50% 50% 45% Maple Street Service Line 15% Gas Slope

  33. Using The Soil Purger In The Pinpointing Process • Purge from a hole where you know that the leak is not • Plug holes near purge point • Dense soil or moisture – time the purge/purge each hole • Use it only when all other methods have failed

  34. Test Methods • Combustible gas indicator 1. Top & bottom of hole 2. Time the readings • Natural ventilation 1. Wait…let holes vent • Blow pipe – vapors/soap top of hole • Odor

  35. Use Of Soil Purger • Should not be used on every leak • Operation: 1. In the pinpoint process 2. As a safety tool – Never use near foundation of building 3. Residual gas • Choosing a purge point is the key • Techniques

  36. CURB LINE 10% Gas In Sewer Manhole ASH STREET 6” Steel UP

  37. CGI Test CGI Test Gas Readings In Manhole • Is gas in the sewer or just using the manhole as a venting point? • Test top and bottom • Percent gas readings will generally not be sewer gas Manhole

  38. “Make Your Mark” Remember:It is much cheaper to drill than to dig. Do you have enough holes to give you enough information about the leak? Using Your Experience Using Test Results Using System Design

  39. The Dry Hole • Probe along the pipe • Expose all of the pipe, not just the top • Learn from your mistakes • Use the hole to your advantage…no one “hits” them all • Is it our gas?

  40. High School 4” High Pressure Steel 25% gas in sewer manhole K-Street 6” Low Pressure Cast Iron 15% gas @ curb 65 69 71 67

  41. Checking After The Repair • Did we find “the” leak? • Residual gas – when will it go away? • Cleanup/plugging the test holes • Importance of proper documentation

  42. Stray Gas • Is it lighter or heavier than air? • Is there ethane in the sample? • Is it a hazard? • What is sewer gas/decomposition gas? • Natural gas vs. stray gas • Use of charcoal filter • Use of collection bottles/bags • Responsibilities regarding stray gas • “Reasonable person concept”

  43. Methane Nitrogen CO2 Chromatographic AnalysisComparison No Ethane Sewer Gas Ethane Natural Gas

  44. Remember:The Job Is Not Completed • Until all paperwork/documentation is completed: • Neatly • Thoroughly • Accurately • You may do everything right, but you may be judged by what is or is not documented

  45. Be Alert Be Prepared Be Safe

  46. AEGIS Insurance Services, Inc.Thank YouPlease visit our website @www.aegislink.com

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